Adaptive bearing friction compensation based on recent knowledge of dynamic friction (Q760378)

Gimbal bearing friction is a major source of stabilization errors for airborne pointing and tracking systems. This paper describes a novel addition to conventional stabilization techniques. This addition contains a model in system software which predicts real-time friction torque values. This new, dynamic friction model, is adaptively adjusted into agreement with actual friction behavior by processing inputs from conventional system sensors. Measurements from these sensors cause on- line adjustment of model parameters, resulting in 'adaptive' compensator action. The model's output is used to generate an addition to conventional stabilization subsystem commands. The model-referenced compensator operates in a predictive, adaptive, feedforward manner to pre-condition the stabilization subsystem, reducing stabilization errors well below levels which are achievable through conventional feedback operation alone.